Spatial Molecular Engineering of Hole Semiconductors Enables Record Efficiency and Durability in Inverted Perovskite Solar Cells

Conventional small-molecule hole-transporting materials (SM-HTMs), although morphologically robust, typically suffer from limited hole mobility, interfacial energy misalignment, and inefficient charge extraction, which collectively hinder power conversion efficiencies (PCEs) above 25% in inverted perovskite solar cells (PSCs). Herein, breaking from conventional design paradigm, novel spatial molecular engineering was targeted proposed for SM-HTMs to overcome inherent limitations while reinforcing advantages. By spatially exposing the functional heterocyclic core to release its full potential, the tailored WH13 dramatically enhances the perovskite/HTM interfacial interactions, promotes crystallization, and facilitates hole extraction. More importantly, the resultant planar-steric architecture enables long-range π-stacking order while supporting nanocrystal-level film-formation, thereby achieving an optimal balance between charge transport dynamics and morphological features. Consequently, WH13-based inverted PSCs achieve a champion PCE of 26.6% (certified 26.24%) with exceptional operational stability (>99%, ISOS-L-1 500 h), representing the highest efficiency reported to date for SM-HTM-based PSCs. This spatial molecular engineering strategy establishes a generalizable design paradigm for next-generation HTMs, opening a promising pathway toward high-performance, operationally stable, and commercially viable PSCs.